[Demonstration of intraocular leptospira in 4 horses suffering from equine recurrent uveitis (ERU)].

The research paper is about a study that provides concrete evidence of the association between leptospiral infection and equine recurrent uveitis (ERU), a common eye condition in horses. It further reveals that ERU could be a result of a systemic infection by Leptospira interrogans, a bacterial pathogen.

Background and Objectives

• This research study was founded on the longstanding discussion on the potential connection between leptospiral infection and equine recurrent uveitis (ERU), a prevalent eye disorder in horses. ERU, sometimes referred to as ‘moon blindness,’ leads to inflammation in several eye components and is known to recur even after treatment interventions.
• The objective of the study was to isolate and identify leptospira from vitreous samples in horses diagnosed with ERU, strengthening the hypothesis of a pathogenic relationship between ERU and leptospiral infection.

Methodology

• Vitreous samples (the clear, gel-like substance in the eye) were taken from 43 horses that had undergone vitrectomy due to ERU. These were cultured to identify if leptospires were present.
• Furthermore, the study tested vitreous samples from 42 horses and serum samples from 40 of these for specific antibodies to leptospira through a microagglutination test (MAT).

Results

• Of the 43 vitreous samples cultured, leptospires were isolated in 4 samples (approximately 9% of the total). Out of these four, three were identified as serovar grippotyphosa, and one belonged to the serogroup Australis.
• When tested for specific leptospiral antibodies, 81% of the 42 vitreous samples and 83% of the 40 serum samples showed titers of 1:50 or higher. This indicates a strong response to the bacteria, suggesting an infection.
• In total, leptospiral antibodies were present in the serum and the vitreous material of 39 out of 43 horses, or 91%, who had undergone vitrectomy.

Conclusions

• The findings demonstrate for the first time, the in-vivo presence of leptospires in horses affected by ERU. It definitely confirms a leptospiral etiology for ERU.
• This is indicative evidence suggesting that ERU is often a consequence of a systemic infection with Leptospira interrogans.
• The presence of intact leptospires and specific antibodies in the eyes affected by ERU signifies a local immune response (antibody production) to the leptospira organisms and/or their antigens, further confirming the connection between ERU and leptospiral infection.